During certain ophthalmic surgical procedures, a user, such as a surgeon or other medical professional, may need to visualize various parts of a patient's eye. An example eye 100 is illustrated in FIG. 1. The eye 100 includes a globe 102 connected to an optic nerve 104, with the globe divided into an anterior segment 118 and a posterior segment 120. The anterior segment 118 includes a lens 112, a cornea 114, and an iris 116. The posterior segment 120 includes a fundus 108 that defines an interior surface of the eye 100. The fundus 108 includes a retina 122, a macula 124, and an optic disk 130. The posterior segment 120 is filled with vitreous humor 128. The optic nerve 104 extends from the posterior segment 120 of the eye 100. To access the interior of the eye 100, a user may penetrate the globe 102 via an incision in a sclera 126. During a vitreoretinal surgical procedure, for example, the user typically views a central portion of the fundus 108, including the area around a macula 124 and/or an optic disk 130. The user, however, may also be required to view a periphery of the fundus 108, including the area around an equator 106 of the globe 102 and to an ora serrata 110, which defines a border between the retina 122 and more anterior portions of the eye 100.
During a surgical procedure, a user may employ one of three different types of lenses, in combination with a surgical microscope, to view the fundus 108. These include a direct contact lens, an indirect contact lens, and an indirect non-contact lens. A direct contact lens allows a user to view a central portion of the fundus 108. However, viewing the periphery of the fundus 108 is not possible with a direct contact lens because it provides only a narrow field of view. An indirect contact lens provides a wider field of view than a direct contact lens. However, indirect contact lenses may be top-heavy and typically move in angular and positional orientation after initial placement on the eye. Accordingly, a user usually requires the help of an assistant, either to continually hold the indirect contact lens in place or to frequently reposition the lens many times during the course of the surgical procedure. These inefficiencies make the indirect contact lens an unpopular choice among some users. Further, because there is an inverse relationship between retinal resolution and retinal field of view, the resolution of the observed fundus decreases as the field of view increases. Relatively lower resolution may make the surgical procedure more challenging for the user.
Some of the positional instabilities associated with the indirect contact lens may be addressed by an indirect non-contact lens, which is attached to the surgical microscope instead of being contacted directly to the eye. However, the indirect non-contact lens may not provide as wide of a field of view of the fundus as the indirect contact lens. In order to see beyond the region of fundus viewable with the indirect non-contact lenses, the surgeon may indent a peripheral region of the sclera to push the fundus in that region into the lens's field of view or may rotate the eye off-axis, or both. Rotating the eye may include moving the patient's head into an uncomfortable manner. Having to frequently rotate the eyeball and/or depress the sclera to view peripheral regions of the fundus is undesirable because it may cause more trauma for the patient, may constitute extra steps for the user to perform, may increase the surgery time, and may increase the likelihood of surgical complications.